Rounded hairstyle worn by Jimi Hendrix and Sly Stone (4)
I believe the answer is:
afro
(Other definitions for afro that I've seen before include "Of hair style, tightly curled and bushy" , "Tightly-curled 4 down" , "Hair cut" , "Luxuriant (black) hairstyle" , "Curly hairstyle" .)